This invention relates to improvements in a multi-layer hose preferably usable for a fuel hose of an automotive vehicle, and more particularly to a multi-layer hose having a strong adhesiveness between layers while having an excellent fuel permeation resistance against fuel such as an alcohol-containing fuel.
Mainly in the United States, the emission control for hydrocarbon-based evaporative emissions from automotive vehicle fuel systems has been strictly tightened, and therefore rubber hoses for fuel having various structures have been developed to meet the control. Particularly in order to achieve a sealability, a fuel permeation resistance and a flexibility which are required in a connecting pipe, a rubber hose commonly proposed has a structure where rubber materials serving as inner and outer layers are laminated on a fuel-barrier resinous material serving as intermediate layer.
As proposed in Japanese Unexamined application publication No. 2004-506548, multi-layer hoses which have been widely employed are provided by disposing fluoroelastomer (FKM) or acrylonitrile butadiene (NBR) as an inner layer, ternary copolymer fluorothermoplastic THV (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoridate) as an intermediate layer (a fuel-barrier layer), and epichlorohydrin rubber (ECO) and acrylonitrile butadiene (NBR) as an outer layer. Additionally, it is commonly known that such multi-layer hoses can include further layers formed of chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CPE) or the like on the outer layer.